The present invention is generally directed to an intra-urethral device and method for making and using the same. More particularly, the present invention is directed to an intra-urethral device that can be used to inhibit leakage of urine due to incontinence. A device of the present invention can have a shape corresponding to the urethral orifice and also include an insertion element to facilitate self-insertion.
Urinary incontinence is the inability of a person to control urine flow. Incontinence may result for a variety of reasons, such as anatomical abnormalities and neurological disorders. Nerve injury, childbirth, and a congenitally short urethra are all common causes of incontinence in woman. Bladder control problems are also a common cause of incontinence and affect twice as many women as men. Loss of bladder control is not a natural part of aging, although its frequency increases with aging, thus limiting the activity of many older persons.
The female urinary system is composed of two kidneys, two ureters, one bladder and one urethra. The urinary tract begins at the kidneys, continues through the ureters to the bladder, and from the bladder to the urethra, through which urine exits the body. The kidney filters the blood to remove waste and produces urine. The ureters, approximately 30 cm in length, extend from the base of the kidneys and pass through the bladder wall into the bladder itself. The bladder is a hollow muscular organ with a volume capacity of approximately 350-450 ml in a normal adult. Continence is maintained during the filling phase because urethral pressure remains greater than intravesical (bladder) pressure. When the bladder""s capacity is reached, the musculature of the bladder contracts, pushing the urine through an opening in the base of the bladder to the urethra (Chisholm and Fair, Scientific Foundations of Urology, Oxford: Heinemann Medical Books, pp. 272-285, 1990).
The urethra in females is approximately 3-4 cm long and has an average inner diameter of 8 mm, varying in diameter from 4-10 mm throughout its length. A cross section of the average urethra would show that the innermost layer of the urethra hangs in folds during rest. When urine flow occurs, the urethra widens and shortens, pulling the folds back into a circular cross section. The urethra constitutes an inner, mucous-producing epithelial lining (urothelium) surrounded by a longitudinal layer of smooth muscle, which in turn is surrounded by a heavy layer of circular smooth muscle fibers. These circular smooth muscles constitute the true involuntary urethral sphincter. External to this are circular striated (voluntary) C-shaped muscles, which surround the middle third of the urethra and comprise the voluntary sphincter known as the rhabdosphincter. The pelvic floor musculature acts as a sling to keep pelvic organs in place and functioning properly.
The urinary system works to ensure that a person can control micturition. As the bladder fills, muscles stretch and nerves signal the brain that the bladder is full, leading to the urge to urinate. In continent persons, a voluntary decision is then made whether or not to urinate. When it is desirable to not urinate, the spinal cord transmits the message from the brain telling the external sphincter to contract. As the external sphincter contracts, it signals the bladder to relax and the bladder neck to stay closed, and the urge to urinate subsides. Additionally, the contraction of the sphincter increases the intraurethral pressure, such that it is greater than the intravesical pressure, thereby preventing urine passage through the urethra. This difference between the intravesical pressure and the intra-urethral pressure is termed the urethral closure pressure. When a person desires to void, the brain signals the external sphincter to relax, decreasing pressure in the urethra until urethral pressure is less than the intravesical (bladder) pressure and flow ensues.
Incontinence, or the inability to retain urine, can be broadly divided into five types. Stress incontinence results from an increase in intra-abdominal pressure, which is translated to the bladder, and for which the rhabdosphincter and pelvic floor muscles cannot compensate. Urge incontinence is a sudden need to urinate that is so urgent it cannot be controlled. This may be associated with spasm of the bladder muscle. Mixed incontinence patients experience both stress and urge incontinence. Overflow incontinence occurs when the bladder fails to empty completely due to obstruction. Small amounts of urine are lost because the bladder neck cannot remain closed against the full bladder. The last type of incontinence, functional incontinence, results when mobility limitations prevent the patient from getting to the bathroom; this is often compounded by spinal and/or nerve injury.
The present invention is designed to prevent the leakage of urine caused by incontinence, which may result from an increase in intra-abdominal pressure due to activities such as coughing, laughing, sneezing and exercising or, alternatively, can be caused by weakened pelvic floor muscles, a weakened external sphincter, a urethra which has lost muscle tone, or an abnormally short urethra.
There are currently many prosthetic devices available to compensate for incontinence. Many of the devices, however, cause urinary tract infections. Some tend to slip or migrate during use and end up in the bladder, where they may cause a great deal of harm and require invasive surgical procedures for removal. Other devices are permanent devices, which require surgery for implementation and have long term biocompatibility problems.
For instance, U.S. Pat. No. 5,131,906 to Chen discloses a device including a centrally disposed rod or tube member, a truncated spherical shell depending from one end of the member, and a plurality of elastic bands uniformly spaced around the shell periphery. Moreover, U.S. Pat. No. 5,090,424 to Simon et al. discloses a flexible urethral plug including a soft inflatable plastic catheter and a transportable fluid which is moved from an external bellows to inflate the catheter within the urethra to block urine flow. Another example of such a device is disclosed in U.S. Pat. No. 5,306,226 to Salama. Salama relates to a urine tube extending through a balloon which is inflated in the neck of the bladder to seal the urethra.
However, in contrast to the present invention, all of the above devices suffer from common disadvantages, including a susceptibility to urine encrustation and provision for direct entry of bacteria into the bladder. Additionally, the spherical design of the aforementioned devices may not totally prevent urine leakage. Because of the fluid mechanics inherent with the spherical design, back pressure caused by urine in the bladder may compress a spherical device, while simultaneously causing the urethral walls to expand, allowing urine to leak.
Other prior art incontinence control devices include devices permanently installed within the urethra, such as those disclosed in U.S. Pat. No. 5,114,398 to Trick et al.; U.S. Pat. No. 5,004,454 to Bevar et al.; and U.S. Pat. No. 5,140,999 to Ardito. However, these devices also suffer from some significant disadvantages including the requirement for surgical implantation, inclusion of metal parts subject to corrosion by urine, and need for patient manipulation to permit urination, which may introduce bacteria into the urethra.
Furthermore, temporary incontinence plugs have been previously described by U.S. Pat. No. 5,082,006 to Jonasson and by Nielson et al., xe2x80x9cThe Urethral Plug: A New Treatment Modality for Genuine Urinary Stress Incontinence in Women,xe2x80x9d Journal of Urology 144: 1199-1202 (1990). The Jonasson device comprises an oblong shaft having at least one knob arranged at a distance from the proximal end of the shaft. This device permits undesirable leakage, however, of approximately 15 ml of fluid. Additionally, the device also allows bacteria to enter the urethra. The device disclosed by Nielson et al. comprises a tubular shaft having at least one 7 mm sphere located along the shaft. This device has, however, been shown to slip during use, allowing the device to migrate into the bladder and requiring surgical removal. Additionally, this device has no sealing mechanism to prevent urine outflow.
In response to the need for a sealing mechanism, a urethral plug, as described in a Master""s thesis entitled xe2x80x9cDesign of an Intra-Urethral Device for Incontinence,xe2x80x9d by Elizabeth M. Burke (Clemson University Department of Bioengineering, December 1996), was developed to better inhibit urine leakage. In particular, as shown in FIG. 1, a plug 10 can be positioned in urethra 22, such that the open end of plug 10 faces bladder lumen 23, allowing urine to enter the hollow cavity of plug 10. The pressure exerted by urine within the hollow cavity against the plug""s sidewalls causes the sidewalls to outwardly flex in a radial direction and form a seal at urethral wall 25. An extractor element 70 can then be used to remove plug 10 from the urethra when desired.
Nevertheless, while these devices have attempted to address the problem of incontinence, none have been totally successful. In particular, the devices above do not sufficiently inhibit urine leakage and are not typically easily insertable into a urethra in a sterile manner. In view of the disadvantages associated with current treatments for incontinence, a need currently exists for a temporary device to control incontinence that is biocompatible and easily insertable by the patient in a sterile manner. A need also exists for a temporary device to control incontinence that can form a seal between the device and the intra-urethral wall to substantially inhibit urine leakage and that will not move or slip during use.
The present invention recognizes and addresses the foregoing disadvantages, and others of prior art constructions and methods.
Accordingly, it is an object of the present invention to provide an intra-urethral device for use in substantially inhibiting urinary leakage due to incontinence in women.
It is another object of the present invention to provide a flexible urethral plug for use in substantially reducing urinary leakage due to incontinence.
Yet another object of the present invention is to provide a device that can be used in conjunction with a urethral plug to facilitate the insertion of the plug from a urethra.
Still another object of the present invention is to provide a mechanism for enhancing the sterility of the urethral plug during the insertion process.
These and other objects of the present invention are achieved by providing a urethral plug that can be inserted into a urethra to substantially inhibit urinary leakage. The urethral plug can provide a resistance to the surrounding muscles as they contract, thus potentially enabling the muscles to strengthen. However, the urethral plug generally does not slip or migrate during use. A plug of the present invention can also be designed to release easily at certain pressures, or when manually removed, by engaging an elongated flexible extractor element.
In general, a urethral plug of the present invention can include a body configured to be insertable into the female urethra to form a substantial blockage against urine flow. For instance, in one embodiment, the urethral plug can have an oblong-shaped structure so as to better conform to the contours of the urethral cavity. The urethral plug can generally be made from any of a variety of materials. Typically, the urethral plug is made from a biocompatible material that may also be elastomeric, if desired. Examples of suitable materials include, but are not limited to, polyurethane, silicone, natural rubber, polyester, chloroprene, polybutadiene, etc.
In one embodiment of the present invention, the urethral plug can also be provided with various mechanisms to facilitate self-insertion of the plug from the urethra. For example, in one embodiment, the urethral plug can be used in conjunction with an insertion element, such as a shaft. In general, the insertion element can comprise a variety of materials, such as polyolefins (e.g. polypropylene), polyamides, semi-rigid rubber materials (e.g. polyurethane).
As stated, to facilitate the insertion of the urethral plug into a urethra, the insertion element can be used in conjunction with the urethral plug. For instance, in one embodiment, the urethral plug can define an opening having a closed distal end and an open proximal end such that the urethral plug can be positioned within the urethra. The shaft can be placed within the opening such that the insertion element and plug can be positioned within a urethra by utilizing the insertion element as a guide. After inserting the urethral plug, the insertion element can then be removed. For example, in one embodiment, the user can hold the urethral plug against the outer wall of the urethra while simultaneously pulling the insertion element in an outwardly direction.
In general, the withdrawal of the insertion element from the urethral can also aid in inhibiting urinal leakage. In particular, as the insertion element is withdrawn from the urethral plug, a vacuum can be created within the tip of the plug such that the tip becomes deformed. For example, the collapsible tip can deform such that the tip is inverted into a cup shape having a concave surface. In one embodiment, this concave surface can face the bladder so that a seal between the concave surface and bladder can effectively form due to fluid and rhabdosphincter pressures. It has been discovered that this seal can effectively inhibit urinal leakage.
Besides withdrawal of the insertion element, other mechanisms can be utilized to ensure that the tip of the plug becomes inverted or deformed so as to form a seal with the urethral wall. For example, in one embodiment, the insertion element can include a hollow center and an opening that is positioned near the end of the element first inserted into the urethral canal. Upon withdrawal, a vacuum pressure that is large enough to completely deform the tip is not typically created. However, the tip will become completely deformed upon application of the slightest amount of pressure, such as the pressure exerted by the flow of urine. Thereafter, upon complete deformation, a seal can be formed with the urethral wall.
Moreover, a variety of mechanisms can also be provided to allow the urethral plug to remain substantially sterile prior to and during insertion. For instance, in one embodiment, an enclosure can be provided as a cover for at least a portion of the urethral plug. Thus, as the plug is inserted through the urethra, the enclosure can collapse around the outer end of the plug. In another embodiment, a roll-out device can also be provided to enhance the ability of the plug to remain sterile during insertion into the urethra. Typically, the roll-out device includes a rolled position and an unrolled position. For example, while in the rolled-position, the roll-out device can be attached to one end of the urethral plug and inserted into the urethra. During insertion, the roll-out device can transform into the unrolled position, in which previously rolled-up material can become unraveled and substantially cover the entrance area of the urethra. Accordingly, the plug does not generally come into contact with any non-sterile surface during insertion, and thus, does not drag substantial amounts of bacteria, fungi, or other pathogenic microorganisms into the urethra.
Other objects, features and aspects of the present invention are discussed in greater detail below.